GB2441508A

GB2441508A - Stand mixer with heating and thermal sensing means

Info

Publication number: GB2441508A
Application number: GB0617634A
Authority: GB
Inventors: Mark Seidler
Original assignee: Kenwood Ltd
Current assignee: Kenwood Ltd
Priority date: 2006-09-08
Filing date: 2006-09-08
Publication date: 2008-03-12
Also published as: GB0617634D0

Abstract

A stand mixer arrangement 10 includes a mixer having a pedestal 20 with a platform 30 for supporting a mixing bowl and an electric motor and a drive system, including a drive outlet 43 disposed overhead of the bowl, capable of imparting a planetary mixing action to tools suspended into the bowl. The mixer also incorporates a heater 71, such as an induction heater, so that ingredients in the bowl can be heated whilst being subjected to the planetary mixing action. A thermal sensing device 80 is provided to enable the temperature of the ingredients to be monitored and controlled; the device comprising a probe 80 which protrudes through the bowl-supporting platform and is resiliently urged upwards to contact the base of the bowl. The probe takes the form of an elongate, metallic member 82, which is sleeved 83 over a substantial part of its length with a thermally resistive material to shield it from the heat generated by the heater. The sleeve is made of a plastics material, an outer surface of which is either coated with or incorporates a non-stick substance, to facilitate repeated movement of the probe with sliding contact relative to an aperture 34 in the bowl-supporting platform. The bowl-supporting surface of the platform is preferably coated with or impregnated by a non-stick material to facilitate the repeated rotational sliding movement between the base of the bowl and the platform, each time the bowl is fitted to, or removed from, the platform.

Description

1 2441508

IMPROVEMENTS IN OR RELATING TO STAND MIXER

ARRANGEMENTS

This invention relates to arrangements including stand mixers, by which is meant the kind of kitchen machine in which a mixing bowl is supported on a pedestal which also supports an electric motor and a drive system including a drive outlet, overhead of the bowl, which permits a planetary mixing action to be imparted to tools suspended into the bowl from the overhead drive outlet.

: . Such stand mixers, such as the Kenwood Chef kitchen machine, are well known and have been well established in use for many years. Over the years, mixers of this kind have been adapted and developed so as to S...

*: perform an ever broadening range of functions, and many such devices incorporate, for example, a plurality of drive outlets running at different speeds and with differing torque characteristics enabling them to perform S...

a wide spread of operations.

Our co-pending UK patent applications Nos. GB0602151.3 and GB0603 934.1, the disclosures of which are intended to be incorporated herein by reference, describe and claim stand mixer arrangements with a still broader operational capability; such arrangements including a mixer having a pedestal for a mixing bowl; an electric motor and a drive system including a drive outlet disposed overhead of the bowl, capable of imparting a planetary mixing action to tools suspended into the bowl therefrom; and heating means provided to permit, in accordance with user selection, ingredients in the bowl to be heated whilst being subjected to the planetary mixing action.

The inventions in the aforesaid UK patent applications encompass the provision of any degree of heating; for example sufficient to completely cook, to partially cook, or to merely warm ingredients. It will be understood in this respect that the degree of heating is influenced both by the heater power (wattage) used in any given situation and the time for which the heat is applied.

: . Some such stand mixer arrangements are intended primarily for attended S... . use, thus the heater power, which is normally adjustable, may conveniently be pre-set, or controlled by the user during a given heating * : *.: process, and the time for which such heating is applied may again be pre-set, by means of an "end-of-cycle" timer, or determined ad hoc by the user. The power and timing control facilities necessary for such I...

operations are similar to those provided for conventional cookery using a range, hob or oven.

The added operational facilities provided by stand mixer arrangements of the kind under consideration here, however, open up various more sophisticated possibilities for food preparation which place significantly higher demands upon the heating and timing controls used.

In any event, however, there is a need with stand mixers of the kind specified for accurate measurement of the temperature of the mixing bowl and its ingredients, and it is one object of this invention to provide a stand mixer arrangement incorporating a particularly efficient and convenient thermal probe detector device for sensing the temperature of a mixing bowl and/or its ingredients.

According to the invention from one aspect there is provided a stand mixer arrangement including a mixer having a pedestal with a platform for supporting a mixing bowl; an electric motor and a drive system including a drive outlet disposed overhead of the bowl, capable of imparting a planetary mixing action to tools suspended into the bowl therefrom; and heating means provided to permit ingredients in the bowl to be heated whilst being subjected to the planetary mixing action; the arrangement further comprising thermal sensing means including a probe protruding through the bowl-supporting platform and urged upwardly by resilient means to contact the base of the bowl in use of the arrangement; * 15 wherein the probe comprises an elongate metallic member sleeved over a :. substantial part of its length with a thermally resistive material S...

S.. substantially unresponsive to the heat developed by said heating means.

In particularly preferred embodiments of the invention, the heating means comprises an induction heater and the probe is adapted to resist absorption of heat from the energy field generated by the heater by reducing the diameter of the elongate metal member over a substantial part of its length and providing said sleeve around the part of reduced diameter.

In some such embodiments, the sleeve substantially compensates for the said reduction in diameter; thereby providing a probe which, with the sleeving in place, is of a substantially constant diameter throughout its length. Further preferably, the largest diameter part of the metallic member is at its head, in the region of contact of the probe with the base of the mixing bowl.

The sleeve may conveniently be made of a non-metallic material such as plastics material.

The plastics or other material may be coated with, or may incorporate, a non-stick substance, such as PTFE, to facilitate repeated movement of the : s probe with sliding contact relative to an aperture in the bowl-supporting platform. S... * S *5*S

Temperature readings derived from the probe may be displayed visually on the stand mixer or elsewhere and may include textual or graphic indications conveyed to the user by means of a display, such as a liquid S...

crystal display (LCD).

In either event, the temperature readings may be conveyed to the display by hard wiring or they may be transmitted to the display wirelessly, for example by means of radio frequency signalling techniques andlor by means of Bluetooth protocols.

In some preferred embodiments of the invention, the heating means can be automatically controlled by temperature feedback signals derived from the probe to comply with user-input instructions for certain operational cooking programmes.

Conveniently, the stand mixer further incorporates a microprocessor and cooking operations are facilitated by pre-programniing the microprocessor with a series of pre-determined operational cooking and mixing sequences, any of which can be selected by the user pressing one of a plurality of special function keys, thereby causing the stand mixer to implement the desired operational programme without requiring the user to input all of the individual instructions.

When the planetary mixing action is to be used intermittently during a cooking programme, it is preferred in some embodiments of the invention that the electric drive motor is operable in a "soft-start" mode, whereby the motor speed is increased in a controlled manner from a relatively low starting speed, in order to reduce the risk of splashing or otherwise ejecting hot ingredients out of the bowl or causing them to separate. This facility may be user-selectable by means of a special key. S...

In still further embodiments of the invention, the arrangement is further provided with a receiver for radio frequency (RF) control signals from a remote control handset (not shown) which permits the stand mixer to be instructed to perform, or be conditioned to perform, some at least of its functions remotely. In other embodiments, remote control signals for the stand mixer are input by means of a suitable device into the mains wiring and sent to the stand mixer over that wiring.

The bowl may conveniently be made of metal, and may conform to existing stand mixer design and shape criteria, so as to be capable of using conventional mixing tools.

Preferably, the bowl is formed so as to provide, at least in certain areas thereof, thermal insulation utilised to create relatively cool areas for handling. In this respect, the bowl may be formed with one or more handles extending outwardly from its upstanding wall; the bowl may be formed with multiple skins with air or another thermally insulative material in the gap between the skins; and/or the bowl may be formed with one or more areas of thermally insulative material. *... * .

One or more regions on the outer surface of the bowl may be coated or S...

*: otherwise treated with a thermochromic material, which adopts a :..15 particular colour when hot, or which otherwise renders visible a warning * message or logo, so as to warn users of areas which should not be *. * I I...

handled.

In accordance with a feature considered inventive of itself, but which can if desired be used with advantage in association with any or all of the previously-recited features, the bowl-supporting surface of the platform may be coated with or impregnated by a non-stick material such as P1'FE, or the said surface may be covered by a film of said non-stick material, thereby to facilitate the repeated rotational sliding movement between the base of the bowl and the platform, each time the bowl is bayonet-fitted to the or removed from the platform.

Where used with a probe of the kind described hereinbefore, the PTFE is preferably apertured to accommodate passage of the probe therethrough, and through the platform, and is configured in the vicinity of the aperture so as to provide a bearing surface for the probe.

In order that the invention may be clearly understood and readily carried into effect, certain embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 shows, in perspective view, a stand mixer in accordance with one example of the invention; * * Figure 2 shows the stand mixer of Figure 1 from a frontal elevation; ****** :*.. 15 Figure 3 shows a side elevation of the stand mixer of Figure 1; and Figure 4 shows one example of a bowl for use with the stand mixer; the bowl being shown in elevation in Figure 4a and in cross-sectional view in Figure 4b.

Referring now to Figures 1, 2 and 3, in which corresponding features carry the same reference numbers, a stand mixer 10 comprises a pedestal which supports a bowl platform 30 and a housing 40. The housing 40 encloses, in conventional fashion, an electric drive motor (not shown) and gearing (not shown) which conveys the motive power supplied by the motor to a plurality of drive outlets to which various tools can be attached to perform a wide variety of tasks in the kitchen.

In this particular example, there is provided a high-speed blender drive outlet behind covers 41, a slow-speed mincer drive outlet behind cover 42 and a planetary drive, intended for food mixing, overhead of the bowl location, at 43, although it will readily be appreciated that more, fewer and/or different drive outlets can be provided in accordance with desired functionality of the stand mixer.

A shanked mixing tool, attached as is conventional, to a socket 44 of the outlet 43, will depend in use into a mixing bowl placed on the bowl platform 30, and is configured to rotate about both the axis of the socket 44 and the central axis 45 of the outlet 43, thus performing a planetary mixing action. The necessary relationships between the relative shapes *... . and dimensions of the bowl and the mixing tool to ensure thorough and S....

repeatable mixing of ingredients are well known and established in use : * over many years. * . **..

As shown, the stand mixer 10 is, in this example, provided with a pair of latches 31, 32 within a recess 33 provided in the bowl platform 30, which latches co-operate with components on the base of the bowl to form a bayonet latching system which ensures firm and ready location of the bowl on its platform. Other latching systems, such as screw-threading for example, can be used as an alternative to bayonet latching if preferred.

The upright part 46 of the housing 40 is configured with a break line 47, and a suitable mechanism to permit the top part 48 of the stand mixer to be hinged away from the platform 30 end of the pedestal part 20, in order to facilitate the insertion and removal of the mixing tools and the bowl.

A first example of an arrangement in accordance with the present invention will now be described with additional reference to Figure 4, which shows a bowl 60 configured and dimensioned to be received in the stand mixer 10 with its base 61 located in the recess 33 of the bowl platform 30. The base 61 of the bowl 60 is formed with a diametrically opposed pair of shaped slots, such as 62, respectively disposed and configured to co-operate with the latching elements 31, 32 of the stand mixer 10 to perform the aforementioned bayonet latching function. * *

As shown schematically by dashed outline in Figure 1, a heater 71 is integrated into the base of the stand mixer 10, beneath the platform 30.

S.....

* 15 The heater 71 is, in this example of the invention, an induction heater of a kind known per Se. *.*. * * S...

The stand mixer 10 also has a thermal sensor for measuring the temperature of the bowl 60, and thus of the contents thereof. The thermal sensor comprises, in this example, a probe 80 protruding through a centrally-located aperture 34 in the bowl-supporting platform 30 and urged upwardly by resilient means (not shown) to contact the base of the bowl 60 in use of the arrangement. Typically, and preferably, the bowl is provided with a recess 63, in the centre of the base 61, into which the head 81 of the probe 80 engages when the bowl 60 is placed, as for use, on the platform 30. The probe 80 comprises an elongate aluminium member 82 which is integral with the head 81 and is sleeved, at 83, over a substantial part of its length with a thermally resistive material substantially unresponsive to the energy field generated by the induction heater 71.

The probe 80 is, in this example, adapted to resist absorption of heat from the energy field generated by the heater 71 by reducing the diameter of the elongate aluminium member 82 over a substantial part of its length and providing the sleeve 83 around the part of reduced diameter.

As shown, the radial thickness of the sleeve 83 is such as to compensate for the reduction in diameter of the aluminium member; thereby providing a probe 80 which, with the sleeving in place, is of a S...

substantially constant diameter throughout its length. In this example, the I..

largest diameter part of the aluminium member 82 is at its head 81, which * 15 is the point at which, in use, contact is established between the probe 80 and the base 61 of the mixing bowl 60. *... * . *..*

The elongate member 82 may, of course, be made of materials other than aluminium, provided that such materials (a) provide adequate thermal transfer to a thermal sensor (not shown) such as a negative temperature coefficient (NTC) sensor, mounted within a hollowed internal region of the member 82 or otherwise associated therewith, to permit reliable temperature measurements to be made, and (b) can tolerate the mechanical and thermal environments in which they have to work in this context. The sleeve 83 may conveniently be made of a non-metallic material, such as a plastics material.

As is known, the supply of power to the inductive heater 71 may be interrupted briefly each time a temperature measurement is taken from the probe 80.

The outer surface of the plastics or other material used for the sleeve 83 may be coated with, or may incorporate, a non-stick substance, such as PTFE, to facilitate repeated movement of the probe 80 with sliding contact relative to the aperture 34, in the bowl-supporting platform 30, through which the probe 80 protrudes.

Temperature readings derived from the thermal sensor associated with the probe 80 may be displayed visually on the stand mixer 10 and/or S...

elsewhere and may include textual or graphic indications conveyed to the user by means of a display, such as a liquid crystal display (LCD) 90 * 15 which, in this case, is carried by the stand mixer 10. S. *S *1 * * S S...

Whether the display is carried by the stand mixer 10 or located elsewhere, the temperature readings may be conveyed thereto either by hard wiring or wirelessly, for example by means of radio frequency signalling techniques and/or by means of Bluetooth protocols.

In some embodiments of the invention, the operation of the heater 71 can be automatically controlled by temperature feedback signals derived from the probe 80 to comply with user-input instructions for certain operational cooking programmes.

A thermal fuse (not shown) may also be provided in the stand mixer 10.

It is preferred that an interlock is provided to prevent the energisation of the heater 71 unless the bowl 60 is in place. Indeed, an interlock may also prevent operation of the electrical drive motor of the stand mixer 10 unless the bowl is in place.

In general, it is preferred that the bowl 60 is made of metal, for example stainless steel, and that it conforms to existing stand mixef design criteria, so as to be capable of using conventional mixing tools.

In this example, the bowl is formed so as to provide, at least in certain S..::: areas thereof, thermal insulation utilised to create relatively cool areas for handling. Optionally, the bowl may be formed with one or more *5:S insulated handles extending outwardly from its upstanding wall; the bowl *S*:$ * 15 may be formed with multiple skins with air or another thermally insulative material in the gap between the skins; and/or the bowl may be formed with one or more areas of thermally insulative material.

Alternatively, or in addition, the outer surface of the bowl, or at least such portions thereof as are likely to be touched by a user, can usefully be coated or otherwise treated with a thermochromic material, which adopts a particular colour when hot, or which otherwise provides or renders visible a warning message or logo, so as to warn users of areas which should not be handled.

The inner surface of the bowl may be coated, or otherwise provided, with non-stick material to guard against unwanted adherence of warmed or cooked ingredients thereto.

Referring again to Figures 1, 2 and 3, it will be noted that the stand mixer is provided with a switch pad 100 presenting user-operable power controls 101 and timer controls 102. The controls 101 and 102 comprise, in this example, digital controls interacting with a microprocessor (not shown) housed at any convenient location within the stand mixer housing. Alternatively, the controls 101 and 102 may be analogue controls or one of them may use digital technology and the other : analogue, depending upon design, cost and other criteria. * *

In this example, the power controls 101 provide control switches such as :: is 103 to provide user-selected instructions to the microprocessor as to the r heating power required and digital timing controls 102 provide control switches 104 for controlling timed operation of the motor-driven planetary drive of the stand mixer and control switches 106 for controlling timed operation of the heating element. The various switches are used to convey user instructions to the microprocessor and it will be appreciated that the microprocessor may be configured to provide internal electronic interlocks to prevent certain combinations of instructions from being implemented. If an operation is prohibited, the user is warned by way of a lamp 110 and a warning buzzer which indicates that an inoperable or inadvisable combination of instructions has been inputted and that the user's operational strategy needs to be revised. In some embodiments of the invention, the warnings may be supplemented with, or replaced by, a visual display, such as a part of the liquid crystal display (LCD) 90 used to convey textual and/or graphic instructions to the user.

Associated with the display 90 are typical resetting and function control buttons 91.

The stand mixer 10 incorporates, in this example, a manually operable speed control adjuster 52 to enable the motor speed, and thus the speed at which the planetary mixing operation is driven, to be set by the user. In some other embodiments, the speed control function is digitised, and the controls therefore are incorporated into the switch pad 100. * S * *5' *S

When the planetary mixing action is to be used intermittently during a *::::* protracted cooking process, it is preferred in some embodiments of the :4 invention that the electric drive motor is operable in a "soft-start" mode, :.u.15 whereby the motor speed is increased in a controlled manner from a * ,.:* relatively low starting speed, in order to reduce the risk of splashing or **** otherwise ejecting hot ingredients out of the bowl or causing them to separate. This facility is user-selectable by means of a special key 105, and is particularly desirable as the cooking process nears conclusion, since relatively high temperatures are then likely to prevail and moreover the ingredients are then likely to have softened and be generally of reduced viscosity, thus more likely to be splashed or otherwise ejected from the bowl.

In some embodiments, the stand mixer is provided with a receiver, for example in the form of an antenna formed on or coupled to a window 120 in the casing 20, for radio frequency (RF) control signals from a remote control handset (not shown) which permits the stand mixer to be instructed to perform, or be conditioned to perform, some at least of its functions remotely. In other embodiments, remote control signals for the stand mixer are input by means of a suitable device into the mains wiring and sent to the stand mixer over that wiring.

According to a feature of the invention which is considered inventive of itself, but which can if desired be used with advantage in association with any or all of the previously-described features of the subject arrangement, the bowl-supporting surface 33 of the platform 30 may be coated with or impregnated by a non-stick material such as PTFE, or the surface 33 may ** S. be covered by a film of such non-stick material, thereby to facilitate the *. repeated rotational sliding movement between the base 61 of the bowl 60 :4 and the platform 30, each time the bowl 60 is bayonet-fitted to, or removed from, the platform 30. S... * S...

Where used with a probe such as 80, the PTFE is preferably apertured to align the aperture 34 for passage of the probe 80 through the platform 30, and is configured in the vicinity of the aperture so as to provide a bearing surface for the probe 80.

The PTFE film or other PTFE-bearing material used for such purpose is sealed around its outer surface into the well 33 so as to provide an outer seal resistant to the ingress of liquids into the casing 20 beneath the platform 30. The sliding contact between the probe 80 and the PTFE or PTFE-bearing material adjacent the aperture 34 provides an inner seal.

Claims

Claims: 1. A stand mixer arrangement including a mixer having a

pedestal with a platform for supporting a mixing bowl; an electric motor and a drive system including a drive outlet disposed overhead of the bowl, capable of imparting a planetary mixing action to tools suspended into the bowl therefrom; and heating means provided to permit ingredients in the bowl to be heated whilst being subjected to the planetary mixing action; the arrangement further comprising thermal sensing means including a probe protruding through the bowl-supporting platform and urged :.. upwardly by resilient means to contact the base of the bowl in use of the *S.. *

arrangement; wherein the probe comprises an elongate metallic member *::* sleeved over a substantial part of its length with a thermally resistive material substantially unresponsive to the heat developed by said heating means.

I
2. An arrangement according to claim 1, wherein the heating means comprises an induction heater and the probe is adapted to resist absorption of heat from the energy field generated by the heater.
3. An arrangement according to claim 2, wherein the elongate metal member is substantially cylindrical and is formed with a head portion adapted to contact, in use, the base of said bowl and wherein the diameter of the elongate metal member over a substantial part of its length is less than that of the head portion; said sleeve being provided around said part of reduced diameter.
4. An arrangement according to claim 3, wherein the radial thickness of said sleeve substantially compensates for the said reduction in diameter; thereby providing a probe which, with the sleeving in place, is of a substantially constant diameter throughout its length.
5. An arrangement according to any preceding claim, wherein said sleeve is be made of a non-metallic material.
6. An arrangement according to claim 5, wherein said non-metallic material is a plastics material.

S * S * S.. S.
7. An arrangement according to any preceding claim, wherein an *:::* outer surface of said sleeve is coated with, or incorporates, a non-stick *:** substance, to facilitate repeated movement of the probe with sliding .:. contact relative to an aperture in the bowl-supporting platform. *SSS * S *.S*
8. An arrangement according to claim 7, wherein said non-stick substance is PTFE.
9. An arrangement according to any preceding claim, wherein said elongate metallic member is made of aluminium.
10. An arrangement according to any preceding claim, including display means for displaying temperature readings derived from the probe.
11. An arrangement according to claim 10, wherein said display means comprises a display carried by the stand mixer.
12. An arrangement according to claim 10 or claim 11, wherein said display means comprises a liquid crystal display (LCD).
13. An arrangement according to any of claims 10, 11 or 12, wherein the temperature readings are conveyed to the display means by hard wiring.
14. An arrangement according to any of claims 10, 11 or 12, wherein S. the temperature readings are conveyed to the display means wirelessly. *SSS * S S...

*:**
15. An arrangement according to any preceding claim, further comprising control means for automatically controlling the operation of said heating means in response to temperature feedback signals derived S...

from said probe.
16. An arrangement according to any preceding claim, wherein the stand mixer further incorporates a microprocessor pre-progranimed with a series of pre-determined operational cooking and mixing sequences, any of which can be selected by the user pressing one of a plurality of special function keys, thereby causing the stand mixer to implement the desired operational programme without requiring the user to input all of the individual instructions.
17. An arrangement according to any preceding claim, further comprising means adapted to cause said motor to start up relatively slowly when actuated on at least one occasion during an operational sequence of the arrangement.
18. A stand mixer arrangement according to any preceding claim, further comprising a receiver for radio frequency (RF) control signals from a remote control handset whereby the stand mixer can remotely be instructed to perform, or be conditioned to perform, some at least of its functions. * . * **S *S*
19. A stand mixer arrangement according to any of claims 1 to 17, *:::* further comprising means for receiving control signals transmitted thereto * :* 4 over mains wiring to which the mixer is connected and which signals permit the stand mixer to be instructed to perform, or be conditioned to perform, some at least of its functions remotely. *.**
20. An arrangement according to any preceding claim, wherein the bowl is made of metal.
21. An arrangement according to any preceding claim, wherein the bowl is formed so as to provide, at least in certain areas thereof, thermal insulation utilised to create relatively cool areas for handling.
22. An arrangement according to any preceding claim, wherein one or more regions of an outer surface of the bowl is coated or otherwise treated with a thermochromic material, which adopts a particular colour when hot, or which otherwise renders visible a warning message or logo, so as to warn users of areas which should not be handled.
23. An arrangement according to any preceding claim, wherein the bowl-supporting surface of the platform is coated with or impregnated by a non-stick material or the said surface is covered by a film of said non-stick material, thereby to facilitate the repeated rotational sliding movement between the base of the bowl and the platform, each time the bowl is bayonet-fitted to the or removed from the platform.

: ...
24. An arrangement according to claim 23, wherein said non-stick * * matenal is PTFE. * S
25. An arrangement according to claim 23 or claim 24, wherein the : **. * 15 non-stick material is apertured to accommodate passage of the probe **. therethrough, and through the platform, and is configured in the vicinity of the aperture so as to provide a bearing surface for the probe.
26. A stand mixer arrangement including a mixer having a pedestal with a platform for supporting a mixing bowl; an electric motor and a drive system including a drive outlet disposed overhead of the bowl, capable of imparting a planetary mixing action to tools suspended into the bowl therefrom; and heating means provided to permit ingredients in the bowl to be heated whilst being subjected to the planetary mixing action; wherein the bowl-supporting surface of the platform is coated with or impregnated by a non-stick material or the said surface is covered by a film of said non-stick material, thereby to facilitate the repeated rotational sliding movement between the base of the bowl and the platform, each time the bowl is bayonet-fitted to the or removed from the platform.
27. A stand mixer arrangement substantially as herein described with reference to and/or as shown in the accompanying drawings. * ** Is * I...

I I...

S

*5*5S* * I S. S. 1 * * * **S.

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